The present invention is related to reticulated devices for treating liquids, and methods for using the devices to treat liquids. The water treatment devices comprise reticulated structures formed from at least three metals.
Purified water is needed for drinking, bathing, cooking, and general household, industrial, military and medical applications. Purification can include removing or reducing the content in water of undesired biological and/or chemical entities, or neutralizing or counteracting the activity or harmful effects of such entities.
Methods of purification include chemical treatment, such as treatment with chlorine, filtration, reverse osmosis, activated carbon, and ion exchange.
Chemical treatments include the use of compounds containing chlorine. Chlorine is useful in controlling bacteria and is often used in the form of hypochlorous acid or calcium hypochlorite. However, discharge of chlorinated water can cause environmental damage and can damage purification elements such as reverse osmosis filters. Other chemical compounds that have been used for treatment of water, particularly for removal of organic compounds, include potassium permanganate and sodium hydroxide.
Reverse osmosis generally uses a filtration membrane, which allows a liquid such as water to pass through while partially or completely retaining species such as salts. Flow across the membrane is driven by a chemical potential gradient. Membranes used in osmosis can have a chemical charge, imparted by the presence of functional groups such as carboxylic or sulfonic groups on the membrane. Charged membranes that can allow relatively high liquid flux and can remove compounds such as organic materials and color agents are used in modern filtration techniques known as nanofiltration.
Precipitants and coagulants are also known for use in water treatment and purification, and can be used in combination with other agents, as in the water purification composition disclosed in U.S. Pat. No. 5,681,475, the disclosures of which are hereby incorporated herein by reference in their entirety. U.S. Pat. No. 5,681,475 discloses a composition provided in unit-dosage form, that includes a disinfectant-sanitizer; a coagulant precipitant; a dispersion-buffer agent; a primary colloidal flocculant; a secondary colloidal flocculant; an agglomeration matrix and pre-filter; and a bulk ion exchange absorbent.
It is often desirable or necessary to remove heavy metals from a water supply. Metals that enter the water supply from wastewater include copper, chromium, zinc, cadmium, mercury, lead and nickel. Metals can often be removed by chemical precipitation as carbonates, hydroxides or sulfides, or by activated carbon, reverse osmosis or ion exchange.
Recently, metal particulates have been used for water treatment. Typical metals used in particulate form for water purification include zinc and copper, which are useful for treating water containing chlorine and bacteria. U.S. Pat. No. 5,314,623, the disclosures of which are hereby incorporated herein by reference in their entirety, discloses a method for treating fluids that utilizes a bed of metal particles such as aluminum, steel, zinc, tin, copper, and mixtures and alloys thereof. Preferred metals are zinc and copper, which can be combined in the form of an alloy such as brass. While U.S. Pat. No. 5,314,623 discloses that the term xe2x80x9cbrassxe2x80x9d can include copper-zinc alloys which can contain other constituents, such as an alloy of 57% copper/40% zinc and 3% lead, the patent further teaches that silver is not desirable because it is difficult to achieve effective bacteriostatic concentrations and keep within the EPA established guidelines for dissolved silver content, and that the cost of silver can be prohibitive.
A need remains for new and effective treatment methods and devices for water and other liquids, particularly for methods and devices that can effectively remove bacteria. The present invention is directed toward these and other important ends.
According to one aspect of the invention, there is provided a device for treating liquids. The device includes a reticulated structure formed from at least three metals, one of which metals is silver. The metals are preferably in the form of an alloy.
Another aspect of the invention is a device for treating liquids, including a substrate having a reticulated structure, and a laminate of at least three metals disposed upon the substrate. In some embodiments, the substrate is made of a non-metallic material.
In preferred embodiments, the amount of silver present in the laminates and the reticulated structures of the devices of the invention is at least about 0.5 weight percent, based on the total weight of the metals. Also in preferred embodiments, the laminate or reticulated structure includes copper, zinc and silver. In some embodiments of the invention, the amount of silver is at least about 8 weight percent, the amount of zinc is at least about 25 weight percent, and the amount of copper is at least about 40 weight percent, based on the total weight of the metals. In certain highly preferred embodiments, the metals include from about 40 weight percent to about 60 weight percent copper, from about 25 weight percent to about 45 weight percent zinc, and from about 0.5 weight percent to about 25 weight percent silver.
Another aspect of the present invention is a method for treating a liquid that includes passing the liquid through a device including a reticulated structure preferably formed from at least three metals or metal oxides, one of which is silver. In preferred embodiments, two of the metals or metal oxides are selected from the group consisting of copper, platinum, magnesium, aluminum, activated alumina, zinc, tin, titanium and palladium.
A further aspect of the invention is a method of manufacturing a liquid treatment device. The method includes providing a substrate having a reticulated structure, and depositing onto the substrate a laminate comprising at least three metals. The laminate and substrate can be heated so that the substrate at least partially decomposes, forming a reticulated structure comprising the at least three metals.
These and other aspects of the present invention will be apparent to one skilled in the art in view of the following disclosure and the appended claims.